Method for incorporating active agents into a hydrophilic polymer foam

Abstract

The present invention consists of a novel process for the incorporation of one or more water-soluble active agents in a hydrophilic polymer foam. Said process makes it possible in particular to obtain a hydrophilic polyurethane foam exhibiting a gradient of active agents. This process is of particular use when manufacturing hydrophilic polyurethane foams intended for medical, cosmetic and dermocosmetic purposes.

The invention claimed is: 
     
       1. A process for manufacturing a hydrophilic polymer foam exhibiting a gradient of a water-soluble active agent, the process comprising:
 a) deposition of the water-soluble active agent in the form of water-soluble particles on an impermeable nonporous support, 
 b) preparation of a precursor mixture of the foam in the form of an aqueous dispersion comprising either monomers or prepolymers, 
 c) pouring the mixture obtained in stage b) over the water-soluble particles that have been deposited on the support at the end of stage a), wherein said water-soluble particles dissolve in the aqueous dispersion comprising the precursor mixture of the foam, 
 d) polymerization of the precursor mixture in which the water-soluble particles dissolved, and production of the hydrophilic polymer foam incorporating the water-soluble active agent, 
 e) drying the hydrophilic polymer foam, and 
 f) separating the impermeable nonporous support from the foam after the foam has been dried in stage e), 
 wherein 80 to 90% of the total weight of the water-soluble active agent is found in the lower 33% of the total volume of the hydrophilic polymer foam, which is the volume of the foam closest to the impermeable nonporous support, at the end of stage e). 
 
     
     
       2. The process as claimed in  claim 1 , wherein the foam is a hydrophilic polyurethane foam which is obtained with a precursor mixture comprising a prepolymer of poly(alkyleneoxy) polyol type. 
     
     
       3. The process as claimed in  claim 1 , wherein the precursor mixture of the foam comprises a silicone-based surfactant. 
     
     
       4. The process as claimed in  claim 1 , wherein the precursor mixture of the foam comprises a nonionic surfactant. 
     
     
       5. The process as claimed in  claim 1 , wherein the water-soluble active agent is chosen from the group consisting of antibacterial agents, anti-inflammatory agents, keratolytic agents, immunomodulating agents, chelating agents, pH-modifying agents, compounds of the extracellular matrix, agents which promote healing, antiviral agents, antifungal agents and painkillers. 
     
     
       6. The process as claimed in  claim 1 , wherein the water-soluble active agent is urea or hyaluronic acid. 
     
     
       7. The process as claimed in  claim 1 , wherein the impermeable nonporous support is a silicone treated support. 
     
     
       8. The process as claimed in  claim 1 , wherein the water-soluble active agent is a synthetic polysulfated oligosaccharide having from 1 to 4 monosaccharide units, a salt of said polysulfated oligosaccharide, or a complex of said polysulfated oligosaccharide. 
     
     
       9. The process as claimed in  claim 1 , wherein 90% of the total weight of the water-soluble active agent introduced in the process for the manufacture of the hydrophilic polymer foam is found in the lower 33% of the hydrophilic polymer foam. 
     
     
       10. The process as claimed in  claim 1 , wherein the impermeable nonporous support is a silicone-treated polyethylene-coated paper or a silicone-treated polyester film. 
     
     
       11. The process as claimed in  claim 1 , wherein the water-soluble active agent in the form of water-soluble particles is deposited on the support by dusting. 
     
     
       12. The process as claimed in  claim 1 , where the water-soluble active agent in the form of water-soluble particles is deposited on the support in a water-soluble matrix, said water-soluble matrix diffusing into the precursor mixture after coming into contact with the precursor mixture in stage c) to allow the water-soluble active agent in the form of water-soluble particles to dissolve in the precursor mixture.